(a) Field of the Invention
The present invention relates to an aircraft navigational system and method by which an aircraft is caused to travel on the flight paths of two intersecting airways, and more particularly to such a system and method where an aircraft is able to fly along a first airway to a point of intersection with a second airway, which intersection may or may not be a known waypoint, and then to continue its course of travel from the point of intersection along the second airway to the point of final destination.
(b) Background Art
In present day aircraft navigational systems, it is common for a navigational computer of the system to cause the auto-pilot of the aircraft to direct the aircraft to fly along a predetermined flight path which is called an "airway". The airway is generally made up of a number of flight path segments or legs which lead from one "waypoint" to another from the point of departure to the point of destination. These waypoints may correspond to known locations on the ground surface where an actual facility exists, (e.g. a navigational station or NAVAID) or the waypoint could be simply a geographical location which is designated only by its latitude or longitude. In some instances, it is desirable or necessary for the aircraft to fly through a first portion of its flight along one airway to a location where this first airway intersects with a second airway. Then the aircraft will turn off the first airway to travel on the second airway to a destination point on the second airway.
Present day navigational systems are capable of directing the auto-pilot to fly the airplane along the first airway to the point of intersection and then along the second airway to the point of destination under circumstances where there is a waypoint at the intersection of the first and second airways. However, the present day navigational systems do not have the capability of directing the auto-pilot to fly this course under circumstances where the point of intersection of the two airways is not a known waypoint.